• (a.) Of, pertaining to, or designating, a hypothetical sulphacid (called also thioarsenious acid) analogous to arsenious acid, and known only in its salts.
Sulph`ar·se'ni·ous adjective (Chemistry) Of, pertaining to, or designating, a hypothetical sulphacid (called also thioarsenious acid ) analogous to arsenious acid, and known only in its salts.